1. Field of the Invention
The present invention relates to an information recording method, and, more particularly, to an information recording method capable of increasing information reproducing efficiency.
2. Description of the Related Art
Conventionally, various types of information recording media, such as an optical card, magnetic tape, magnetic disk, optical disk, magneto optical (MO) disk and IC card, have been used for recording information.
Of those information recording media, the optical card has parallel recording tracks formed on a card and records information in the form of pits optically formed on the tracks in association with that information. The optical card is one type of write once and read many (WORM) type information recording media which does not allow recorded information to be rewritten.
On each track on the optical card are provided a single sector or a plurality of sectors which are segmented along the track. The number of sectors on each track can be selected arbitrarily from several types prepared in advance, and one sector becomes the smallest unit at the time of recording or reproducing information.
That is, the number of times information can be recorded on one track on an optical card equals the number of sectors provided on that track. For instance, in recording even one-byte information on an optical card as an information recording medium, only this 1-byte information is recorded in one sector.
In recording or reproducing information through reciprocation of the optical card, information recording or reproducing to or from the whole sectors in one track can be done by a single movement (one-way movement), i.e., forward movement or backward movement. The time required for reproduction of the entire information from one track on an optical card with only one sector formed per track therefore equals that in the case where a plurality of sectors are formed in one track.
The substantial amount of information that can be recorded on one track on an optical card with a plurality of sectors per track is normally smaller than that in the case of one sector formed per track, because of an increase in error correction codes due to the error correcting efficiency of the error correction codes and the need for providing a physical gap between sectors or information or the like to identify the delimitation between sectors.
In recording information, whose occurrence is not predictable in terms of time, on a WORM information recording medium such as the above-described optical card, information is normally recorded sequentially using sectors with as small a size as possible among those sectors having larger sizes the size of that information, thus increasing the number of records of information per track.
The aforementioned magnetic tape, one of various information recording media, normally records information in order from the top of the tape to the end. To reproduce different pieces of information located apart from each other on the tape, one piece after the other, the tape should be sent forward or rewound.
The other types of information recording media, the magnetic disk, optical disk and MO disk, are shaped like a disk. Those recording media each rotate on the disk center and have concentric or spiral information recording tracks, allowing relatively easy recording or reproducing of information located far from each other on the recording medium, jumping over tracks, in addition to sequential information recording/reproduction as done on a magnetic tape. The former recording/reproducing of information however needs the time to jump over tracks to the target location as the recording medium rotates, thus requiring more time than in the case of recording or reproducing information on or from adjacent locations.
The last-mentioned IC card as an information recording medium has a central processing unit (CPU) and a semiconductor memory incorporated into a card. Information is recorded or reproduced electrically, and can be rewritten. The information recording or reproduction is executed by giving a write command and recording information to the CPU in the card or giving a read command to this CPU.
It is always possible that part of recorded information is destroyed in information recording on the aforementioned various types of information recording media. To protect information from corruption, the same information is recorded more than twice on the same information recording medium as one protection scheme.
With the same information recorded redundantly, even when one information is destroyed, the target information can be correctly reproduced if the other redundant information is left undamaged.
Recently, various types of databases have been built with a vast amount of information accumulated in each data base. In the medical field, for example, construction of databases on personal information about the results of regular medical checkup, medical treatment records of chronic diseases, or the like has been attempted and those accumulated pieces of personal information have been used in various statistical summing processes or health control of patients by doctors and nurses.
Those databases have been conventionally kept and managed in some institutes or organizations which perform total management of information, such as hospitals, with the necessary information recorded on information recording media having a relatively large memory capacity, such as the aforementioned magnetic tapes, magnetic disks, optical disks or MO disks.
Unless a wide on-line network is fully built, such information managing method does not allow an information user, such as a patient, having his or her information registered in a database, to utilize the accumulated self information if the user does not use the organization where that information is accumulated.
As a solution to this shortcoming, a system has been developed which uses an information recording medium, such as the mentioned optical disk or IC card, having a sufficient memory capacity to store information of one person and excellent in its portability, to record personal information on the medium and allows each user to carry around so that the user can use the self information in different organizations.
For instance, in creating a database of the results of a regular medical checkup conducted by autonomous communities, information on each checkup for individual persons are often collectively recorded. There may be several specific schemes to manage those information. For instance, the information is added to the database as one file or one or multiple records in a specific form. Particularly, in recording information on a WORM type medium, like an optical disk, the recording position of information already recorded cannot be changed, making it inevitable to record information collectively as much as possible in order to keep high recording efficiency.
Such built-up personal data is often used as a reference for doctors, nurses, etc. to give the proper directions or advices to the patients based on the accumulated records of the medical checkups.
In checking and advising many patients in a given period of time as in a group checkup, the time spared for a single patient is limited, so that doctors and nurses cannot actually refer to all the accumulated data for all the patients.
The doctors therefore usually give directions, referring to ordinary data indicative of the health conditions, such as the weight, the value of blood pressure and the value blood sugar, in addition to the latest checkup results.
The required data, such as the old weights, blood pressure values, and blood sugar values, are recorded together with the results of other checkups for each checkup date, and the recording positions of old data are located apart from one another. This lowers the information reproducing efficiency with respect to the time.
For instance, to find out the last ten values of the weight, the information on the weight should be read out from each of ten recording blocks recorded on the information recording medium. With the use of a magnetic tape, it is inevitable to feed the tape forward every time information for one block is obtained, while with the use of a disk-shaped information recording medium or an optical card, track jumping should be performed to access ten locations on the medium.
When an IC card is used, ten information reproducing commands should be issued to the CPU in the card to attain the information on the ten events.
To reproduce information sequentially recorded on the optical card, in particular, the information should be reproduced in order from the first sector where the recording of the information starts. This provides a smaller amount of information obtainable per track, resulting in a lower information reproducing efficiency with respect to the time required for the reproduction.
In the case where one piece of information is recorded more than once, e.g., twice, on the same information recording medium, the area of that information occupying on the information recording medium becomes twice as large as that in the case where no redundant recording is performed, thus reducing the substantial amount of information recordable on the whole information recording medium.